Seasonal Shifts in Surface Water-Groundwater Connections in a Ferricrete-Impacted Stream Estimated from Electrical Resistivity

The efficacy of the hyporheic zone (HZ) — where surface water and groundwater mix — for processing nutrients or uptake of metals is dependent on streambed hydraulic conductivity and stream discharge, among other characteristics. Here, we explore electrical resistivity tomography (ERT) of hyporheic exchange in Cement Creek near Silverton, Colorado, which is affected by ferricrete precipitation. To quantify flows through the HZ, we conducted four-hour salt injection tracer tests and collected time-lapse ERT of the streambed and banks of Cement Creek at high and low flow. We installed piezometers to conduct slug tests, which suggested a low permeability zone at 44-cm depth likely comprised of ferricrete that cemented cobbles together. Based on the ERT, the tracer released into the stream was constrained within the shallow streambed with little subsurface flow through the banks. Tracer was detected in the HZ for a longer time at high flow compared to low flow, suggesting that more flow paths were available to connect the stream to the HZ. Tracer was confined above the ferricrete layer during both the high- and low-flow tests. Mass transfer and storage area parameters were calculated from combined analysis of apparent bulk conductivity derived from ERT and numerical modeling of the tracer breakthrough curves. The hyporheic storage area estimated at low discharge (0.1 m2) was smaller than at high discharge (0.4 m2) and residence times were 2.7 h at low discharge and 4.1 h at high discharge. During high discharge, in-stream breakthrough curves displayed slower breakthrough and longer tails, which was consistent with the time-lapse electrical inversions and One-dimensional Transport with Inflow and Storage (OTIS) modeling. Our findings indicate that ferricrete reduces the hydraulic conductivity of the streambed and limits the areal extent of the HZ, which may lower the potential for pollutant attenuation from the metal-rich waters of Cement Creek.

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Insight into the influence of local streambed heterogeneity on hyporheic-zone flow characteristics

Hydrogeology Journal ◽

10.1007/s10040-020-02244-5 ◽

2020 ◽

Vol 28 (8) ◽

pp. 2697-2712

Author(s):

Robert Earon ◽

Joakim Riml ◽

Liwen Wu ◽

Bo Olofsson

Keyword(s):

Surface Water ◽

Hydraulic Conductivity ◽

Penetration Depth ◽

Hyporheic Zone ◽

Flow Characteristics ◽

Time Lapse ◽

Hyporheic Exchange ◽

Tracer Injection ◽

Hyporheic Flow ◽

Exchange Processes

AbstractInteraction between surface water and groundwater plays a fundamental role in influencing aquatic chemistry, where hyporheic exchange processes, distribution of flow paths and residence times within the hyporheic zone will influence the transport of mass and energy in the surface-water/groundwater system. Geomorphological conditions greatly influence hyporheic exchange, and heterogeneities such as rocks and clay lenses will be a key factor for delineating the hyporheic zone. Electrical resistivity tomography (ERT) and ground-penetrating radar (GPR) were used to investigate the streambed along a 6.3-m-long reach in order to characterise geological layering and distinct features which may influence parameters such as hydraulic conductivity. Time-lapse ERT measurements taken during a tracer injection demonstrated that geological features at the meter-scale played a determining role for the hyporheic flow field. The penetration depth of the tracer into the streambed sediment displayed a variable spatial pattern in areas where the presence of highly resistive anomalies was detected. In areas with more homogeneous sediments, the penetration depth was much more uniformly distributed than observed in more heterogeneous sections, demonstrating that ERT can play a vital role in identifying critical hydraulic features that may influence hyporheic exchange processes. Reciprocal ERT measurements linked variability and thus uncertainty in the modelled resistivity to the spatial locations, which also demonstrated larger variability in the tracer penetration depth, likely due to local heterogeneity in the hydraulic conductivity field.

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Electrical resistivity dynamics beneath a fractured sedimentary bedrock riverbed in response to temperature and groundwater–surface water exchange

Hydrology and Earth System Sciences ◽

10.5194/hess-21-3105-2017 ◽

2017 ◽

Vol 21 (6) ◽

pp. 3105-3123 ◽

Cited By ~ 8

Author(s):

Colby M. Steelman ◽

Celia S. Kennedy ◽

Donovan C. Capes ◽

Beth L. Parker

Keyword(s):

Electrical Resistivity ◽

Surface Water ◽

Water Exchange ◽

Winter Season ◽

Time Lapse ◽

Specific Conductance ◽

Low Flow ◽

Invasive Technique ◽

Thermal Transients ◽

Thaw Cycle

Abstract. Bedrock rivers occur where surface water flows along an exposed rock surface. Fractured sedimentary bedrock can exhibit variable groundwater residence times, anisotropic flow paths, and heterogeneity, along with diffusive exchange between fractures and rock matrix. These properties of the rock will affect thermal transients in the riverbed and groundwater–surface water exchange. In this study, surface electrical methods were used as a non-invasive technique to assess the scale and temporal variability of riverbed temperature and groundwater–surface water interaction beneath a sedimentary bedrock riverbed. Conditions were monitored at a semi-daily to semi-weekly interval over a full annual period that included a seasonal freeze–thaw cycle. Surface electromagnetic induction (EMI) and electrical resistivity tomography (ERT) methods captured conditions beneath the riverbed along a pool–riffle sequence of the Eramosa River in Canada. Geophysical datasets were accompanied by continuous measurements of aqueous specific conductance, temperature, and river stage. Time-lapse vertical temperature trolling within a lined borehole adjacent to the river revealed active groundwater flow zones along fracture networks within the upper 10 m of rock. EMI measurements collected during cooler high-flow and warmer low-flow periods identified a spatiotemporal riverbed response that was largely dependent upon riverbed morphology and seasonal groundwater temperature. Time-lapse ERT profiles across the pool and riffle sequence identified seasonal transients within the upper 2 and 3 m of rock, respectively, with spatial variations controlled by riverbed morphology (pool versus riffle) and dominant surficial rock properties (competent versus weathered rock rubble surface). While the pool and riffle both exhibited a dynamic resistivity through seasonal cooling and warming cycles, conditions beneath the pool were more variable, largely due to the formation of river ice during the winter season. We show that surface electrical resistivity methods have the capacity to detect and resolve electrical resistivity transience beneath a fractured bedrock riverbed in response to porewater temperature and specific conductance fluctuations over a complete annual cycle.

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Covariance-constrained difference inversion of time-lapse electrical resistivity tomography data

Geophysics ◽

10.1190/geo2015-0491.1 ◽

2016 ◽

Vol 81 (5) ◽

pp. E311-E322 ◽

Cited By ~ 11

Author(s):

Thomas Hermans ◽

Andreas Kemna ◽

Frédéric Nguyen

Keyword(s):

Electrical Resistivity ◽

Electrical Resistivity Tomography ◽

Time Lapse ◽

Breakthrough Curves ◽

Time Dimension ◽

Resistivity Tomography ◽

Shallow Subsurface ◽

Direct Measurements ◽

Active Processes ◽

Low Sensitivity

Hydrogeophysics has become a major field of research in the past two decades, and time-lapse electrical resistivity tomography (ERT) is one of the most popular techniques to monitor passive and active processes in shallow subsurface reservoirs. Time-lapse inversion schemes have been developed to refine inversion results, but they mostly still rely on a spatial regularization procedure based on the standard smoothness constraint. We have applied a covariance-based regularization operator to the time-lapse ERT inverse problem. We first evaluated the method for surface and crosshole ERT with two synthetic cases and compared the results with the smoothness-constrained inversion (SCI). These tests showed that the covariance-constrained inversion (CCI) better images the target in terms of shape and amplitude. Although more important in low-sensitivity zones, we have observed improvements everywhere in the tomograms. Those synthetic examples also show that an error made in the range or in the type of the variogram model had a limited impact on the resulting image, which still remained better than SCI. We then applied the method to cross-borehole ERT field data from a heat-tracing experiment, in which the comparison with direct measurements showed a strong improvement of the breakthrough curves retrieved from ERT. This method could be extended to the time dimension, which would allow the use of CCI in 4D inversion schemes.

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Electrical Resistivity Dynamics beneath a Fractured Sedimentary Bedrock Riverbed in Response to Temperature and Groundwater/Surface Water Exchange

10.5194/hess-2016-559 ◽

2016 ◽

Author(s):

Colby Steelman ◽

Celia S. Kennedy ◽

Donovan Capes ◽

Beth L. Parker

Keyword(s):

Electrical Resistivity ◽

Surface Water ◽

Water Exchange ◽

Low Flow ◽

Rock Properties ◽

Invasive Technique ◽

Rock Surface ◽

Groundwater Temperature ◽

Thermal Transients ◽

Thaw Cycle

Abstract. Bedrock rivers occur where surface water flows along an exposed rock surface. Fractured sedimentary bedrock can exhibit variable groundwater residence times, anisotropic flow paths, heterogeneity, along with diffusive exchange between fractures and rock matrix. These properties of the rock will affect thermal transients in the riverbed and groundwater–surface water exchange. In this study, surface electrical methods were used as a non-invasive technique to assess the scale and temporal variability of riverbed temperature and groundwater–surface water exchange beneath a sedimentary bedrock riverbed. Conditions were monitored on a semi-daily to semi-weekly interval over a full annual period that included a seasonal freeze-thaw cycle. Surface electromagnetic induction and electrical resistivity imaging methods captured conditions beneath the riverbed along a pool-riffle sequence within the Eramosa River, Guelph, Ontario, Canada. Geophysical datasets were accompanied by continuous measurements of aqueous specific conductance, temperature and river stage. Vertical temperature profiling conducted in an inclined borehole underlying the river revealed active groundwater flow zones through fracture networks within the upper 10 m of rock. Resistivity measurements during cooler high-flow and warmer low-flow conditions identified a spatiotemporal riverbed response that was largely dependent upon riverbed morphology and groundwater temperature. Time-lapse resistivity profiles collected across the pool and riffle identified seasonal transients within the upper 2 m and 3 m of rock, respectively, with spatial variations controlled by riverbed morphology (pool verses riffle) and dominant surficial rock properties (competent verses weathered rock rubble surface). While the pool and riffle both exhibited a dynamic resistivity through seasonal cooling and warming cycles, conditions beneath the pool were more dynamic, largely due to the formation of river ice. Although seasonal resistivity trends beneath the riverbed suggest groundwater discharge may be influencing the spatiotemporal extent of a groundwater-surface water mixing zone, intraseasonal resistivity transience suggest potential groundwater–surface water exchange across the upper few meters of rock.

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Characterization of groundwater and surface water mixing in a semiconfined karst aquifer using time-lapse electrical resistivity tomography

Water Resources Research ◽

10.1002/2013wr013991 ◽

2014 ◽

Vol 50 (3) ◽

pp. 2566-2585 ◽

Cited By ~ 27

Author(s):

Steven B. Meyerhoff ◽

Reed M. Maxwell ◽

André Revil ◽

Jonathan B. Martin ◽

Marios Karaoulis ◽

...

Keyword(s):

Electrical Resistivity ◽

Surface Water ◽

Electrical Resistivity Tomography ◽

Karst Aquifer ◽

Time Lapse ◽

Resistivity Tomography ◽

Water Mixing

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Long term changes in the functioning of a karst aquifer under anthropogenic forcing

10.5194/egusphere-egu21-10846 ◽

2021 ◽

Author(s):

Cousquer Yohann ◽

Jourde Hervé

Keyword(s):

Surface Water ◽

Flow Rate ◽

Climatic Variability ◽

Karst Aquifer ◽

Active Management ◽

Low Flow ◽

Spring Discharge ◽

Long Term Changes ◽

And Storage

A quantitative estimation of the sustainability of groundwater resources is a challenge for water supplies. This study focuses on karstic hydro systems, which provide water resources to a large part of the Mediterranean population. Here, we address the long-term changes in the functioning of the Lez karst aquifer, which has been providing water to the city of Montpellier since the XIXth century. &#160;Before 1965, only the natural overflow of the spring was used, then pumping in the spring, down to -6.50 m below the overflow level of the spring, was performed until 1981. After this date, the management of the water resource consisted in pumping groundwater at a much greater flow rate (up to 2000 l/s) than the natural discharge during low flow (200 l/s), which seasonally generates important drawdowns (down to ~25 m) at regional scale.The available time series consist in more than 70 years of discharge and water table (with some gaps) that encompass the three kinds of groundwater management, spanning from a passive management to the current active management. The change in water budget terms over time (before and after active management) highlights the modification of transfers and storage in the different karst compartments (epikarst, unsaturated zone, saturated zone), and the climatic variability of precipitation, evapotranspiration at inter-annual. A lumped parameter model was set up in order to simulate spring discharge, while accounting for surface water and grandwater level dynamics, and better assess the changes in the storage dynamics within the different compartments (matrix-conduits) of the karst. A robust parameter estimation, accounting for groundwater discharge and surface water discharge observations, has been conducted using a Monte-Carlo procedure. In order to obtaines a robust model, divers data type such as groundwater flow, surface flow and water level, have been used. [H1]&#160; Once the model was calibrated over (1955-2020) reference period, several prospective management scenarios based on pumping discharge were simulated with an estimation of predictive uncertainty. This allowed evaluating the influence of pumping at large flow rate (active management) on the flux and storage on matrix-conduits exchanges of such karst hydrosystem. A modification on both the discharge rates and the direction of water exchanges between compartments, and especially between matrix and conduits, have been noted. The importance of climatic variability at inter-annual scale on water availability has been discussed as well.

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Time-lapse imaging of subglacial drainage conditions using three-dimensional inversion of borehole electrical resistivity data

Journal of Glaciology ◽

10.3189/172756506781828854 ◽

2006 ◽

Vol 52 (176) ◽

pp. 49-57 ◽

Cited By ~ 11

Author(s):

Bernd Kulessa ◽

Bryn Hubbard ◽

Giles H. Brown

Keyword(s):

Electrical Resistivity ◽

Hydraulic Conductivity ◽

Three Dimensional ◽

Clay Content ◽

Time Lapse ◽

Sediment Layer ◽

Bulk Resistivity ◽

Resistivity Data ◽

Hydrological Cycles ◽

Subglacial Drainage

AbstractWe recorded electrical resistivity data at the base of four boreholes drilled through Haut Glacier d’Arolla, Switzerland. The data were acquired repetitively every hour over two diurnal hydrological cycles in the late melt season, separated by 10 days. Constrained three-dimensional (3-D) data inversion allowed reconstruction of hourly variations in bulk resistivity in the subglacial sediment layer. Inverted resistivity models reflect the establishment of channelized subglacial drainage in the study area between the two hydrological cycles, in agreement with previous work. Daily variations in bulk and water resistivity are in phase, and bulk resistivity amplitudes decrease away from the subglacial channel. Using selected electrical–hydraulic relationships, we estimate metre-scale changes in the hydraulic conductivity and porosity of the subglacial sediment layer, accounting for increasing clay content and decreasing median grain radius with distance from the channel. Hydraulic conductivity and porosity were respectively calculated to decrease from (6.4 ± 2.1) × 10–2ms–1 and 0.34 ± 0.01 at the channel to (3.3 ± 2.2) × 10–2ms–1 and 0.26 ± 0.01 at a distance of 5m from it. The hydraulic conductivity estimates are in agreement with previously inferred values, and the porosity estimates fall within the expected range for unlithified subglacial sediments. We conclude that collection and inversion of repeat 3-D subglacial resistivity data is feasible and has the capacity to generate multidimensional images of subglacial hydraulic processes and properties.

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